diff --git a/buildbot_nix/__init__.py b/buildbot_nix/__init__.py
index bd8f2704e..ecb631aef 100644
--- a/buildbot_nix/__init__.py
+++ b/buildbot_nix/__init__.py
@@ -7,6 +7,7 @@
 from collections import defaultdict
 from collections.abc import Generator
 from dataclasses import dataclass
+from datetime import UTC, datetime
 from pathlib import Path
 from typing import TYPE_CHECKING, Any
 
@@ -194,13 +195,14 @@ def schedule_eval_failure(
         return (self.failed_eval_scheduler, props)
 
     def schedule_cached_failure(
-        self, job: NixEvalJobSuccess, report_status: bool
+        self, job: NixEvalJobSuccess, report_status: bool, first_failure: datetime
     ) -> tuple[str, Properties]:
         source = "nix-eval-nix"
 
         props = BuildTrigger.set_common_properties(
             Properties(), source, job, report_status
         )
+        props.setProperty("first_failure", str(first_failure), source)
 
         return (self.cached_failure_scheduler, props)
 
@@ -440,32 +442,29 @@ def run(self) -> Generator[Any, Any, None]:
             # check which jobs should be scheduled now
             schedule_now = []
             for build in list(build_schedule_order):
+                failed_build = failed_builds.check_build(build.drvPath)
                 if job_closures.get(build.drvPath):
                     pass
-                elif (
-                    failed_builds.check_build(build.drvPath)
-                    and self.build.reason != "rebuild"
-                ):
-                    failed_builds.remove_build(build.drvPath)
+                elif failed_build is not None and self.build.reason != "rebuild":
                     scheduler_log.addStdout(
-                        f"\t- skipping {build.attr} due to cached failure\n"
+                        f"\t- skipping {build.attr} due to cached failure, first failed at {failed_build.time}\n"
                     )
                     build_schedule_order.remove(build)
 
                     brids, results_deferred = yield self.schedule(
                         ss_for_trigger,
-                        *self.schedule_cached_failure(build, self.report_status),
+                        *self.schedule_cached_failure(
+                            build, self.report_status, failed_build.time
+                        ),
                     )
                     scheduled.append(
                         BuildTrigger.ScheduledJob(build, brids, results_deferred)
                     )
                     self.brids.extend(brids.values())
-                elif (
-                    failed_builds.check_build(build.drvPath)
-                    and self.build.reason == "rebuild"
-                ):
+                elif failed_build is not None and self.build.reason == "rebuild":
+                    failed_builds.remove_build(build.drvPath)
                     scheduler_log.addStdout(
-                        f"\t- not skipping {build.attr} with cached failure due to rebuild\n"
+                        f"\t- not skipping {build.attr} with cached failure due to rebuild, first failed at {failed_build.time}\n"
                     )
 
                     build_schedule_order.remove(build)
@@ -514,7 +513,7 @@ def run(self) -> Generator[Any, Any, None]:
 
             # if it failed, remove all dependent jobs, schedule placeholders and add them to the list of scheduled jobs
             if result != SUCCESS:
-                failed_builds.add_build(job.drvPath)
+                failed_builds.add_build(job.drvPath, datetime.now(tz=UTC))
 
                 removed = self.get_failed_dependents(
                     job, build_schedule_order, job_closures
@@ -705,7 +704,13 @@ def run(self) -> Generator[Any, object, int]:
         # show eval error
         error_log: StreamLog = yield self.addLog("nix_error")
         error_log.addStderr(
-            f"{attr} was failed because it has failed previous and its failure has been cached.\n"
+            "\n".join(
+                [
+                    f"{attr} was failed because it has failed previously and its failure has been cached.",
+                    f"  first failure time: {self.getProperty('first_failure')}",
+                ]
+            )
+            + "\n"
         )
         return util.FAILURE
 
diff --git a/buildbot_nix/failed_builds.py b/buildbot_nix/failed_builds.py
new file mode 100644
index 000000000..1b004b16c
--- /dev/null
+++ b/buildbot_nix/failed_builds.py
@@ -0,0 +1,61 @@
+import dbm
+from datetime import datetime
+from pathlib import Path
+from typing import TYPE_CHECKING, Any
+
+from pydantic import BaseModel
+
+if TYPE_CHECKING:
+    database: None | dbm._Database = None
+else:
+    database: Any = None
+
+
+class FailedBuildsError(Exception):
+    pass
+
+
+class FailedBuild(BaseModel):
+    derivation: str
+    time: datetime
+
+
+DB_NOT_INIT_MSG = "Database not initialized"
+
+
+def initialize_database(db_path: Path) -> None:
+    global database  # noqa: PLW0603
+
+    if not database:
+        database = dbm.open(str(db_path), "c")
+
+
+def add_build(derivation: str, time: datetime) -> None:
+    global database  # noqa: PLW0602
+
+    if database is not None:
+        database[derivation] = FailedBuild(
+            derivation=derivation, time=time
+        ).model_dump_json()
+    else:
+        raise FailedBuildsError(DB_NOT_INIT_MSG)
+
+
+def check_build(derivation: str) -> FailedBuild | None:
+    global database  # noqa: PLW0602
+
+    if database is not None:
+        if derivation in database:
+            # TODO create dummy if deser fails?
+            return FailedBuild.model_validate_json(database[derivation])
+        return None
+    raise FailedBuildsError(DB_NOT_INIT_MSG)
+
+
+def remove_build(derivation: str) -> None:
+    global database  # noqa: PLW0602
+
+    if database is not None:
+        del database[derivation]
+    else:
+        raise FailedBuildsError(DB_NOT_INIT_MSG)